1. Field of the Invention
This invention generally relates to offshore pipeline repair, particularly to adjustable templates for determining a relative position between two randomly oriented pipe ends, and more specifically, to adjustable template apparatus and methods for modeling the dimension and contour of a segment of piping to be installed between two randomly oriented pipe ends.
2. Description of the Related Art
Oil, gas, and other hydrocarbons from a producing well are typically transported through a subsea pipeline extending along the ocean floor of a reservoir. Such subsea pipeline is often exposed to extreme environmental conditions which can result in damage to a section of the pipeline. Repairs made to subsea pipeline typically include cutting and removing damaged pipe sections, generally performed by divers. Prior to surfacing, the divers typically take measurements in order to estimate the relative position between the two open pipe sections which may or may not match measurements of the removed damage pipe section. A replacement segment of piping is then fabricated for placement between the two open pipe sections.
In the distant past, the trial-and-error approach was the method of choice employed in order to form a replacement segment of pipe that adequately fit between the two open pipe sections. This was found to be extremely costly and the prepared segment was found to be prone to leaks. Later, various other methodologies were employed to try to more accurately measure the distance and relative orientation between the two open pipe sections. One methodology that has been employed in the past includes utilization of a measurement device employing a telescopic extension bar between the two mating flanges, which is adjusted and then tightened using a single wing nut and/or adjusted through use of a hand-tight clamp. Recognized by the inventor, however, is that, although relatively simple in design, the length of the telescopic extension bar cannot be precisely secured, and thus, can result in substantial inaccuracies. Inaccurate measurements are very costly in the offshore environment as section replacement can involve a very large barge and a significant amount of diving related assets and time. Inaccurate measurements can result in a requirement to modify the replacement section, which can be time-consuming and extremely expensive in diver time, barge time, and lost production. Accordingly, recognized by the inventor is the need for a measurement device that has very efficient securing mechanisms to avoid slippage of the connecting parts for measuring the linear distance between pipe ends.
There are also other limitations to the conventional designs. For example, the above described conventional design causes an inherent limitation in the length of separation between the two open pipe sections that can be measured, which can be problematic. Specifically, as the design is relatively old, the design does not appear to include any provisions needed to account for the large size flowlines, which have become more common in recent years. Even when used in smaller flowlines, no accommodations are made where the spacing exceeds the maximum telescopic extension capability. Accordingly, recognized by the inventor is the need for a measurement device that includes provisions for adding-on sections to extend a telescopic length bar for measuring the linear distance between pipe ends for lengthy subsea spools encountered during subsea pipeline repair.
Conventional designs of a measurement device are known to use swivel flanges which rotate about a pivot ball to match the flange faces orientation. Recognized by the inventor, however, is that such swivel flanges are not only costly, the “pivot ball” is difficult to lock. Therefore, it very difficult to guarantee the measured position of miter degree and rolling offset when using such device. Also, such conventional measurement device does not include provisions for marking the flange twist angles for reference. As such, any even slight accidental movement of the pivot ball, once the template is lifted from seabed for fabrication, causes major discrepancies which require expensive re-fabrication.
Recognized, therefore, is the need for a measurement device that is suitable for use during construction of any size flow line as well as for the repair of subsea trunk lines where very long pipe spools are required to be fabricated, and that is simpler than conventional measuring devices, that contains less moving parts, and that can be used by non-skilled divers.
Also recognized is the need for a measuring device that uses vertical and horizontal positioning plates with robust securing mechanisms such as, for example, two spanner locknuts, and that includes position marking planes that guarantee rigidity of the template and marking reference. Further, recognized is the need for a measuring device that employs a backing plate with bolt holes that can be rotated to match the rotation of the existing flange hole centers, which can allow for the use of standard weld neck flanges that are more cheaper and readily available in the market. Recognized by the inventor is that such design can advantageously produce very precise results from the first attempt due to better securing mechanisms, and can allow pipeline fabricators to easily recognize changes in the template initial position due to lifting, as the fabricators can readily identify, for example, any loose locknuts or changed marks.